In recent years, the porphyrin derivatives exhibiting photosensitizing activity and affinity for cancer cells when employed in conjunction with irradiation of laser light, can increasingly produce excellent results in the diagnosis and treatment of cancer (T. J. Dougherty, "Porphyrin Localization and Treatment of Tumors", pp. 75-78 (1984)]. For this purpose, frequently use is made mainly of hematoporphyrin or hematoporphyrin derivative. However, the former compound is difficult to be obtained in the pure state [R. K. DiNello et al., "The Porphyrins", vol. 1, pp. 297-298 (1978)]., whereas the latter is produced by acetylating the former, followed by treatment with alkali and acid and consists of a mixture of several kinds of porphyrin derivatives. Accordingly, such porphyrins are considered to present significant problems in clinical application.
At present, the hematoporphyrin derivative, the utilization of which is being tried in the diagnosis and treatment of cancer, is obtainable only in a mixture of several kinds of different compounds as mentioned in the above. This renders it quite difficult to obtain the compound of invariably constant quality and consequently constitutes great difficulty in conducting tests on the efficacy or toxicity and the like. In order to solve such problem, it is considered important to obtain the pure porphyrin derivative that can demonstrate both photosensitizing activity and affinity for cancer cells.